1. Field of Invention
The invention relates to an embroidery data processing apparatus, and in particular to a technique associated with retrospective control under which previous embroidery data is restored which corresponds to a certain editing action selected from a plurality of editing actions that have been executed, during generation or editing of embroidery data representing an embroidery pattern to be formed by an embroidering machine, and a technique associated with re-execution control under which previously executed editing actions that follow the selected editing action are re-executed.
2. Description of Related Art
Embroidery data processing apparatuses have been put to practical use, which apparatuses generate or edit embroidery data composed of stitch position data to be supplied to an embroidering machine so as to form an embroidery pattern. Such an embroidery data processing apparatus is generally constructed such that a keyboard, a display, a coordinate input device (e.g., mouse), an image reading device (image reader), a printer, and other similar equipment, are connected to a main control unit of a personal computer.
The embroidery data processing apparatus is adapted to generate embroidery data representing a desired embroidery pattern, by reading a drawn sketch or design through an image reader, or plotting the pattern on a display using a mouse. When generating embroidery data in such manners or correcting or editing the thus generated embroidery data, the embroidery data processing apparatus is able to perform various editing actions, including rotating actions, moving actions, enlarging or reducing actions, lateral or vertical inverting actions, and so forth.
Where such editing actions as "UPWARD MOVE", "RIGHT MOVE", "90.degree. CLOCKWISE ROTATE", "LATERAL MIRROR (inversion)", and "ENLARGE (120%)" are successively performed on generated embroidery data representing an image of a "panda", for example, the names of these editing actions are successively stored as an edit history in the order of execution of the actions. In the meantime, the pattern of the "panda" represented by the latest embroidery data resulting from the editing actions appears on a display. Upon looking at the pattern on the display, the user may wish to change the degree of rotation, the third one of the five editing actions that have been executed, namely, change "90.degree. CLOCKWISE ROTATE" to "75.degree. CLOCKWISE ROTATE", for example.
In this case, if an "UNDO" key is operated once, embroidery data obtained just after execution of the editing action "LATERAL MIRROR" (one step prior to the latest state) can be restored based on the edit history, and, if the "UNDO" key is operated twice, embroidery data obtained after execution of the editing action "RIGHT MOVE" (two steps prior to the latest state) can be restored. In this state, the rotation angle is set to "75.degree.", and, after "75.degree. CLOCKWISE ROTATE" is executed, the previously executed editing actions "LATERAL MIRROR" and "ENLARGE (120%)" are designated one by one, and re-executed, thereby to generate final embroidery data of the "panda" that has been rotated clockwise by 75.degree. and enlarged to 120% of the original.
In the known embroidery data processing apparatus, embroidery data representing a pattern to be formed by an embroidering machine is generated or edited with reference to the pattern on a display, and the UNDO key is provided which is operated to restore embroidery data to the state before execution of the latest or last-executed editing action. When a certain editing action selected from the previously executed editing actions, for example, the third one as counted from the latest editing action, is to be corrected or changed, therefore, the UNDO key needs to be operated a plurality of times so as to restore embroidery data to the state three or four steps before the latest action for correction thereof, resulting in a reduced operating efficiency. Also, each time the UNDO key is operated, a certain amount of time is needed for computing embroidery data in the state one step before the latest action. If the UNDO key is to be operated many times, therefore, a large amount of computing time is required, resulting in a reduced operating efficiency in the correcting procedure.
Furthermore, after embroidery data corresponding to the selected editing action is restored by operating the UNDO key, and the editing action is corrected or changed as desired, the plurality of editing actions that followed the selected editing action are re-designated one by one, and the editing actions are successively re-executed. Thus, a re-executing operation is required for each of the editing actions following the correction, resulting in reduced operating ease or efficiency.